The present invention relates generally to aluminum alloys and more specifically to L12 phase dispersion strengthened aluminum alloys having ceramic reinforcement particles.
The combination of high strength, ductility, and fracture toughness, as well as low density, make aluminum alloys natural candidates for aerospace and space applications. However, their use is typically limited to temperatures below about 300° F. (149° C.) since most aluminum alloys start to lose strength in that temperature range as a result of coarsening of strengthening precipitates.
The development of aluminum alloys with improved elevated temperature mechanical properties is a continuing process. Some attempts have included aluminum-iron and aluminum-chromium based alloys such as Al—Fe—Ce, Al—Fe—V—Si, Al—Fe—Ce—W, and Al—Cr—Zr—Mn that contain incoherent dispersoids. These alloys, however, also lose strength at elevated temperatures due to particle coarsening. In addition, these alloys exhibit ductility and fracture toughness values lower than other commercially available aluminum alloys.
Other attempts have included the development of mechanically alloyed Al—Mg and Al—Ti alloys containing ceramic dispersoids. These alloys exhibit improved high temperature strength due to the particle dispersion, but the ductility and fracture toughness are not improved.
U.S. Pat. No. 6,248,453 discloses aluminum alloys strengthened by dispersed Al3X L12 intermetallic phases where X is selected from the group consisting of Sc, Er, Lu, Yb, Tm, and U. The Al3X particles are coherent with the aluminum alloy matrix and are resistant to coarsening at elevated temperatures. The improved mechanical properties of the disclosed dispersion strengthened L1F2 aluminum alloys are stable up to 572° F. (300° C.). U.S. Patent Application Publication No. 2006/0269437 A1 discloses an aluminum alloy that contains scandium and other elements.
Amorphous alloys have received interest in recent years because materials with an amorphous structure are usually very strong and corrosion resistant in comparison with crystalline structures having the same composition. However, amorphous aluminum alloys have been found to have lower ductility and fracture toughness than the crystalline form. Aluminum based amorphous alloys with high strength and low density are desirable because of their lower density and their applicability in the aerospace and space industries. Amorphous aluminum alloys would also be useful in armor applications where lightweight materials are desired.